Embolism, infraction, shock

Question 1

What are the 3 common circulatory disorders?

Answer 1

• Embolism
• Infraction
• Shock

Question 2

What is the concept of Embolism?

Answer 2

• An embolus is a mass of material in the vascular system able to become lodged within a vessel and block its lumen

Question 3

What is the most common type of embolism?

Answer 3

• Pulmonary embolism, from deep leg vein thrombosis

Question 4

Where does the term thromboembolism come from?

Answer 4

• Most of the emboli are form dislodged thrombus, hence the term thromboembolism

Question 5

What location is the outcome of Embolism?

Answer 5

• The outcome depends on where the emboli originate and where they lodge

Question 6

What are the sources of emboli?

Answer 6

• Pieces of thrombus, mixed thrombus and blood clot
• Infected lesions within the bloodstream
• Gas bubbles e.g. air, N2 (divers transferred rapidly from high to low-pressure environments)
• Fat, bone marrow (in bone fractures)
• Tumour cells
• Others: amniotic fluid (during labour)

Question 7

What % of Pulmonary Embolism are small and clinically silent?

Answer 7

• 60% - 80%

Question 8

What can Pulmonary embolism cause?

Answer 8

• Can cause sudden death, right heart failure, cardiovascular collapse
• If the blockage is in a middle size vessel, it can cause pulmonary haemorrhage
• Multiple emboli over time may cause pulmonary hypertension

Question 9

What is Systemic arterial emboli?

Answer 9

• Emboli arise in the arterial circulation
• ~80% from intracardiac mural thrombi
• ~10-15% of unknown origin
• Can travel to a wide variety of sites
• In general, arterial emboli cause tissue infraction

Question 10

Systemic arterial emboli can travel to a wide variety of sites, what does the site of lodge depend on?

Answer 10

• The site of lodge depends on the source and the relevant amount of blood flow that downstream tissues receive

Question 11

What is infraction?

Answer 11

• An infarct is an AREA of ISCHEMIC NECROSIS caused by OCCLUSION of either the ARTERIAL SUPPLY or the VENOUS DRAINAGE in a particular tissue

Question 12

Explain the relationship of Tissue infraction and clinical illness and death

Answer 12

• Tissue infraction is a common and very important cause of clinical illness and death

Question 13

Is death of tissue from toxins or trauma infraction?

Answer 13

• The death of tissue from other causes, such as toxins or trauma, is not infraction but simply necrosis

Question 14

What do Infractions result from?

Answer 14

• Nearly 99% of all infracts result from thrombotic or embolic events and almost all result from arterial occlusion
• Other causes: vasospasm, haemorrhage into atheromatous plaque, vessel compression (by tumour), traumatic rupture

Question 15

What does different shapes of infracts reflect?

Answer 15

• Shape reflects the territory of occluded blood supply

Question 16

Name the different shapes of infracts and name the location of the blood supply

Answer 16

• Wedge-shaped: in lung
• Triangular: in kidney
• Scarred: in spleen

Question 17

What is Classification of infracts?

Answer 17

• Classification: Based on their colour (reflecting the amount of haemorrhage) and the presence or absence of microbial infection

Question 18

Explain the different colours of infracts

Answer 18

• White (anaemic): in solid organs with end arterial circulation (such as heart, spleen, and kidney)
• Red (haemorrhagic)
• Septic: Infected infract
• Bland: uninfected infract

Question 19

Name and explain the major factors that influence the outcome of an infraction

Answer 19

• The nature of the vascular supply: The availability of alternative blood supply
• The rate at which an occlusion develops: Slow occlusion provides time for alternative perfusion pathways
• Vulnerability to hypoxia: Neurons and myocardial cells are vulnerable
• The oxygen content of the blood

Question 20

Explain the Evolution of myocardial infract

Answer 20

• Infracted area varies in appearance depending on the time after infraction

Question 21

What is Shock?

Answer 21

• A final common pathway for several lethal clinical events best described as inadequate tissue perfusion

Question 22

What is Shock characterised by and this is due to what?

Answer 22

• Characterised by systemic hypotension due to:
• Reduced cardiac output
• Reduced effective circulating blood volume

Question 23

What is Cardiogenic shock caused by?

Answer 23

• Cardiogenic shock: results from low cardiac output due to heart failure

Question 24

What is the cause of Hypovolaemic shock?

Answer 24

• The result of low cardiac output due to the loss of blood or plasma volume

Question 25

What is the cause of Septic shock?

Answer 25

- Results from vasodilation and peripheral pooling of blood as part of a systemic immune reaction to bacterial or fungal infection

Question 26

What are the symptoms of shock

Answer 26

- Altered conscious state - Restlessness or irritability - Pale or bluish, cool moist skin - Excessive thirst - Rapid and weak pulse - Rapid breathing - Nausea and/or vomiting

Question 27

What is the first aid of shock?

Answer 27

- Place the victim in a shock position - Keep the person warm and comfortable - Turn the victim's head to one side if the neck injury is not suspected